Transformation Process of Five Water in Epikarst Zone: A Case Study in Subtropical Karst Area

Abstract

Five water stand for five forms existence models of water. In Karst area, Five water means precipitation, groundwater, evapotranspiration water, soil water, and overland flow. The complicated water-bearing hydrogeological media and the inhomogeneous water storage structure leads to low efficiency of water utilization. To reveal intricated water resources transformation in karst areas, a typical epikarst zone was selected. The Five water and their conversion processes were studied and the transformation models was built based on the long-term positioning observations. The results show that: (1) Overland flow can be generated when precipitation reaches 6 mm and lasts for 6 h. Under light and moderate rainfall (LMR) conditions, less than 6% of the precipitation is converted to overland flow. Under heavy rainfall and rainstorm (HRR) conditions, the conversion rate is 3.5%-6%. (2) Under the condition of LMR, there are 2%-3.5%, 40%-60% and 25%-35% that transformed to vegetation water, soil water and groundwater respectively, while it is 1.5%-2.2%, 25%-30% and 32%-50% under the condition of HRR. (3) The proportion of precipitation was transformed to soil water is 20%-70%. (4) The conversion rate of groundwater and karst fissure water for LMR conditions are 8%-15% and 10%-15%, and that for HRR is 15%- 20% and 20%-35%. (5) The proportions of different degrees of precipitation transformed into vegetation transpiration and evaporation water are 1.5%-3.5% and 6%-9%, respectively. (6) Generally, about 0%-4% of the precipitation is converted into overland flow, 20%-70% into soil water, 25%-50% into karst groundwater, and 1%-10% into evaporative water.

The Characteristics and Application of Deuterium and Oxygen Isotopes to Karst Groundwater, Southwest China

“…Specifically, the epikarst zone is characterized by strong dissolution, which results in the development of karst fissures and pores. The groundwater stored in these water-bearing media, including fissures, pores, channels, and weathering joints in the strongly weathered zone, is a significant factor in the water cycle [148][149][150]. This plays a pivotal role in water circulation and possesses a powerful storage capacity [84,151,152].…”

Assessment of Huixian Karst Wetland for Local Water Augmentation in Guilin, China

“…The southwest of China, which lies in the center of East Asia and is one of the world's three contiguous karst development regions, is a typical region with a fragile ecological environment [18][19][20][21]. The karst wetlands have appeared to be undergoing serious degradation in the region [22]. Huixian karst wetland, located in the southwest of China, is the largest wetland within the altitude area of middle and low latitude in China and is also a representative of the subtropical karst landscape in the world [23,24].…”